Physiological sensor history backfill system and method

ABSTRACT

A physiological sensor history backfill system and method including a method of sensor history backfill for a local base device operable to wirelessly communicate with a physiological sensor connected to a patient, the method including: obtaining physiological readings for the patient at a predetermined interval; storing the physiological readings at the physiological sensor as sensor physiological readings; storing the physiological readings at the local base device as historic physiological readings; obtaining a current physiological reading for the patient; transmitting the current physiological reading to the local base device in a current reading message; detecting a record gap in the historic physiological readings between the current physiological reading and the historic physiological readings; and filling the record gap in the historic physiological readings with sensor physiological readings from the physiological sensor when the current reading message does not include the sensor physiological readings to fill the record gap.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/304,686 filed Jun. 13, 2014 and issued on Feb.27, 2018 as U.S. Pat. No. 9,901,305, which is herein incorporated byreference.

TECHNICAL FIELD

The technical field of this disclosure is personal physiologicalmonitoring systems, particularly, physiological sensor history backfillsystems and methods.

BACKGROUND OF THE INVENTION

Advances in electronics and telemetry have resulted in theminiaturization of medical devices such that medical devices whichpreviously required large stationary equipment can now be worn about theperson, who can be monitored or receive treatment while pursuing normaldaily tasks.

One area of such advances has been in the treatment of diabetes. Anestimated twenty-six million people in the United States, or about 8% ofthe population, have diabetes. This percentage is expected to increasein the near-term as the population ages. Wearable glucose monitors andinsulin pumps have been developed which allow persons under treatmentfor diabetes to be monitored and receive insulin while carrying on theirday-to-day tasks.

Current portable medical devices such as insulin pumps communicate witha glucose sensor/transmitter device that continuously monitors sensoractivity over a radio frequency network. Small, compact continuousglucose monitors (CGMs) lack a user interface, so the CGMs send sensorinformation as readings to the insulin pump that provide user interfacesto allow the user to monitor these sensor information readings withgraphs, icons, sensor alerts, selectable sensor readings, andstatistical output. The insulin pump saves the sensor readings in asensor history area that can be displayed to the user or downloaded toan external reporting application to provide the user and/or health careprovider with a record of the insulin therapy delivered by the pump asreported by the CGM's sensor readings information.

Unfortunately, noise or interference which occurs when the CGM attemptsto send sensor information to the insulin pump can prevent the insulinpump from receiving the information. Loss of power can also disable theCGM or insulin pump. This results in gaps in the sensor readings storedin the pump's sensor history area. Without this sensor information, theuser interface is unable to provide the user or health care providerwith a complete display of the patient history or a complete record ofthe results of the insulin therapy delivered by the pump.

It would be desirable to have a physiological sensor history backfillsystem and method that would overcome the above disadvantages.

SUMMARY OF THE INVENTION

One aspect of the invention provides a method of history backfill for alocal base device operable to wirelessly communicate with aphysiological sensor connected to a patient, the method including:obtaining physiological readings for the patient at a predeterminedinterval; storing the physiological readings at the physiological sensoras sensor physiological readings; storing the physiological readings atthe local base device as historic physiological readings; obtaining acurrent physiological reading for the patient; transmitting the currentphysiological reading to the local base device in a current readingmessage; detecting a record gap in the historic physiological readingsbetween the current physiological reading and the historic physiologicalreadings; and filling the record gap in the historic physiologicalreadings with sensor physiological readings from the physiologicalsensor when the current reading message does not include the sensorphysiological readings to fill the record gap.

Another aspect of the invention provides a system of history backfillfor a patient, the system including a physiological sensor and a localbase device operable to wirelessly communicate with the physiologicalsensor. The physiological sensor has a processor and the memory operablycoupled to the processor, the memory containing programming codeexecutable by the processor to: obtain physiological readings for thepatient; store the physiological readings at the physiological sensor assensor physiological readings; transmit the physiological readings tothe local base device; obtain a current physiological reading for thepatient; transmit the current physiological reading in a current readingmessage to the local base device; receive a request for missingphysiological readings; select sensor physiological readings for themissing physiological readings; and transmit the selected sensorphysiological readings to the local base device. The local base devicehas a processing unit and a storage medium operably coupled to theprocessing unit, the storage medium containing programming codeexecutable by the processing unit to: receive the physiological readingsfrom the physiological sensor; store the physiological readings ashistoric physiological readings; receive the current physiologicalreading in the current reading message from the physiological sensor;detect a record gap in the historic physiological readings between thecurrent physiological reading and the historic physiological readings;identify the missing physiological readings in the record gap; transmitthe request for the missing physiological readings to the physiologicalsensor when the current reading message does not include the sensorphysiological readings to fill the record gap; receive the selectedsensor physiological readings from the physiological sensor; and fillthe record gap with the selected sensor physiological readings.

Another aspect of the invention provides a method of history backfillfor an insulin pump operable to wirelessly communicate with a glucosesensor connected to a patient, the method including: obtaining glucosereadings for the patient at a predetermined interval, each of theglucose readings being associated with a glucose reading time; storing apredetermined storage number of the glucose readings at the glucosesensor with the associated glucose reading time, the predeterminedstorage number being greater than or equal to one and greater than apredetermined packet number; measuring a current glucose reading for thepatient at a current measurement time; transmitting from the glucosesensor to the insulin pump a current message including the currentglucose reading, the current measurement time, and the predeterminedpacket number of the glucose readings immediately before the currentglucose reading, the predetermined packet number being greater than orequal to zero; retrieving a last stored glucose reading time from theinsulin pump memory; calculating a time gap between the currentmeasurement time and the last stored glucose reading time; setting abackfill start time equal to the last stored glucose reading time whenthe time gap is greater than a packet duration defined as thepredetermined interval multiplied by the predetermined packet number;requesting the glucose sensor to transmit to the insulin pump thepredetermined packet number of the glucose readings immediately afterthe backfill start time; storing the predetermined packet number of theglucose readings immediately after the backfill start time in theinsulin pump; adding the packet duration to the backfill start time; andrepeating the requesting, the storing, and the adding when a backfillend time defined as the backfill start time less the packet duration isless than the current measurement time.

The foregoing and other features and advantages of the invention willbecome further apparent from the following detailed description of thepresently preferred embodiments, read in conjunction with theaccompanying drawings. The detailed description and drawings are merelyillustrative of the invention, rather than limiting the scope of theinvention being defined by the appended claims and equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a physiological sensor and a local basedevice for a physiological sensor history backfill system in accordancewith the invention.

FIG. 2 is a block diagram of a physiological sensor and a local basedevice for a physiological sensor history backfill system in accordancewith the invention.

FIG. 3 is a timing/event chart for physiological sensor history backfillin accordance with the invention.

FIG. 4 is a flow chart of a method of physiological sensor historybackfill in accordance with the invention.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of a physiological sensor and a local basedevice for a physiological sensor history backfill system in accordancewith the invention. In this example, the patient 100 is connected to aphysiological sensor 110 and a local base device 120. The physiologicalsensor 110 is operable to wirelessly communicate with the local basedevice 120 across wireless link 102. Exemplary wireless links 102include radio frequency connections, WiFi connections (such as Wi-Ficonnections using 802.11b/g/n protocols), Bluetooth connections, and thelike. In one embodiment, the physiological sensor 110 is a glucosesensor and the local base device 120 is an insulin pump.

The physiological sensor 110 can be any physiological sensor operable toobtain and store physiological readings for the patient. Exemplaryphysiological sensors 110 include glucose sensors, heart-rate sensors,ECG sensors, pulse oximeters, blood pressure sensors, respiration ratesensors, skin temperature sensors, electroencephalography (EEG) sensors,activity level sensors, vital sign sensors, and the like.

The local base device 120 can be any portable local base device carriedby the patient to interact with the physiological sensor 110 and tostore physiological readings. Exemplary local base devices 120 includeinsulin pumps, cell pumps, local monitors, fitness monitors, smartphones, portable/wearable computing devices, watches, tablets,computers, and the like. The local base device 120 can optionallycommunicate with remote locations over cellular communication networksor the like so that medical personnel or the like can download andanalyze the physiological readings.

FIG. 2, in which like elements share like element numbers with FIG. 1,is a block diagram of a physiological sensor and a local base device fora physiological sensor history backfill system in accordance with theinvention. The physiological sensor 110 can include processor 112, andoperably coupled to the processor 112, memory 114, sensor 116, andtransmitter/receiver 118. The local base device 120 can includeprocessing unit 122, and operably coupled to the processing unit 122,storage medium 124, transmitter/receiver 126, and optional user I/Ointerface 128.

For the physiological sensor 110, the sensor 116 obtains physiologicalreadings from the patient 100. The physiological readings can be storedin the memory 114 as sensor physiological readings. The memory 114 canalso store programming code executable by the processor 112. Thephysiological readings can also be transmitted through thetransmitter/receiver 118 to the local base device 120 over the wirelesslink 102.

For the local base device 120, the transmitter/receiver 126 can receivephysiological readings from the physiological sensor 110 and store thephysiological readings as historic physiological readings in the storagemedium 124. The storage medium 124 can also store programming codeexecutable by the processing unit 122. The patient 100 can use theoptional user I/O interface 128 to provide input to and receiveinformation from the local base device 120.

In one embodiment, the memory 114 of the physiological sensor 110contains programming code executable by the processor 112 to: obtainphysiological readings for the patient; store the physiological readingsat the physiological sensor as sensor physiological readings; transmitthe physiological readings to the local base device; obtain a currentphysiological reading for the patient; transmit the currentphysiological reading in a current reading message to the local basedevice; receive a request for missing physiological readings; selectsensor physiological readings for the missing physiological readings;and transmit the selected sensor physiological readings to the localbase device.

In one embodiment, the storage medium 124 of the local base device 120contains programming code executable by the processing unit 122 to:receive the physiological readings from the physiological sensor; storethe physiological readings as historic physiological readings; receivethe current physiological reading in the current reading message fromthe physiological sensor; detect a record gap in the historicphysiological readings between the current physiological reading and thehistoric physiological readings; identify the missing physiologicalreadings in the record gap; transmit the request for the missingphysiological readings to the physiological sensor when the currentreading message does not include the sensor physiological readings tofill the record gap; receive the selected sensor physiological readingsfrom the physiological sensor; and fill the record gap with the selectedsensor physiological readings.

FIG. 3 is a timing/event chart for physiological sensor history backfillin accordance with the invention. In this example, the local base deviceis an insulin pump and the physiological sensor is a glucose sensorconnected to the patient, the insulin pump being operable to wirelesslycommunicate with the glucose sensor.

The timing/event chart 300 illustrates timing and events for a glucosesensor 302 connected to a patient. An insulin pump 303 is operable towirelessly communicate with the glucose sensor 302 and includes aprocessing unit 304 in communication with a storage medium 306 storingdata and instructions for the insulin pump 303.

At 310, in this example, the glucose sensor 302 is not in wirelesscommunication with the insulin pump 303. The lack of wirelesscommunication can be caused by noise or interference near the patient,with the result that the glucose readings for the patient measured atthe glucose sensor 302 did not reach the insulin pump 303. Because theinsulin pump 303 is not receiving the glucose readings, a record gapdevelops in the historic glucose readings stored in the insulin pump303.

At 312, wireless communication between the glucose sensor 302 and theinsulin pump 303 is restored. The glucose sensor 302 sends a glucosesensor time sync message 314 to the processing unit 304, which returnsan insulin pump time sync message 316 to the glucose sensor 302. Theoptional synchronization procedure synchronizes the insulin pump clockwith the glucose sensor clock after restoration of wirelesscommunication. Even though the time sync is optional here, in oneembodiment, the insulin pump can require the timestamp for each currentglucose sensor reading to be within 2 seconds of the insulin pumptimestamp.

The glucose sensor 302 sends a current reading message 318 including acurrent glucose reading for the patient to the processing unit 304. Inone example, the current reading message can include the current glucosereading, the current measurement time, and a predetermined packet numberof glucose readings immediately before the current glucose reading. Inone example, the predetermined packet number of the glucose readings iseight glucose readings, but any number greater than or less than eightmay be utilized according to embodiments of the present invention. Thecurrent measurement time provides an accurate time for each currentreading message.

At 320, the processing unit 304 determines whether there is a record gapin the historic glucose readings stored in the storage medium 306 suchthat sensor history backfill is required. In one embodiment, theprocessing unit 304 determines that there is a record gap by retrievinga last stored glucose reading time from the storage medium 306; andcalculating a time gap between the current measurement time and the laststored glucose reading time. When the current reading message includesenough sensor glucose readings to fill the record gap, there is no needto obtain additional sensor glucose readings, since the current readingmessage already includes enough information to complete the historicrecord.

When the processing unit 304 determines that there is a record gap inthe historic glucose readings such that sensor history backfill isrequired, the processing unit 304 sends a backfill record request 322starting with the last stored glucose reading time to the glucose sensor302. In response at 324, the glucose sensor 302 returns a firstpredetermined packet number of the glucose readings following the laststored glucose reading time. In one example, the predetermined packetnumber of the glucose readings is eight glucose readings, but any numbergreater than or less than eight may be utilized according to embodimentsof the present invention.

When the processing unit 304 determines that there is a record gap inthe historic glucose readings such that sensor history backfill isrequired, the processing unit 304 can also send a pump history datarequest 326 to the storage medium 306. In response, the storage medium306 returns pump history data 328 following the last stored glucosereading time. The pump history data 328 can include markers for eventsthat occurred during the record gap, such as the patient making a timechange at the insulin pump 303 (Time Change marker), the patientmanually turning off/on the glucose sensor (Sensor Off marker, Sensor Onmarker), changing of the day through the passage of time (Start of Daymarker, End of Day marker), and the like. At 330, the processing unit304 detects the event markers and caches the event markers at theinsulin pump 303. At 332, the processing unit 304 caches thepredetermined packet number of the glucose readings at the insulin pump303. The cached glucose readings fall within the time interval of thepump history data 328. The caching of the predetermined packet number ofthe glucose readings takes advantage of the pump history data structurewhich allows up to eight glucose readings to be written at a time.

At 334, the glucose sensor 302 transmits the glucose reading normallyobtained for the patient at the predetermined interval to the insulinpump 303. Thus, the normal procedure of obtaining glucose readings andstoring them at the glucose sensor and insulin pumps can continue duringthe sensor history backfill procedure. Those skilled in the art willappreciate that the normal procedure can be maintained or suspendedduring the sensor history backfill procedure as desired for a particularapplication.

At 336, the processing unit 304 processes the cached event markers andcached glucose readings, so that each glucose reading being backfilledto the storage medium 306 is associated with the time on the user clock(the local time at the patient's location as entered by the patient) atwhich the glucose reading was obtained. At 338, the processing unit 304stores the backfill records in the storage medium 306 as historicglucose readings. The first backfill record is stored immediatelyadjacent to the record at the last stored glucose reading time.

The backfill procedure continues until the record gap is filled asindicated in the loop portion 340 of the timing/event chart 300. At 342,the processing unit 304 sends another pump history data request to thestorage medium 306, after determining that the cached event markers haveall been used. In response, the storage medium 306 returns pump historydata 344 for the next portion of the record gap to be filled.

At 346, the processing unit 304 detects the event markers and caches theevent markers at the insulin pump 303. At 348, the processing unit 304caches the glucose readings at the insulin pump 303. The cached glucosereadings fall within the time interval of the pump history data 348.

When additional stored glucose readings are required from the glucosesensor 302, i.e., when the cached glucose readings have all been used,the processing unit 304 sends a backfill record request 350 to theglucose sensor 302. In response at 352, the glucose sensor 302 returnsan additional predetermined packet number of the glucose readings. Theloop portion 340 of the timing/event chart 300 can be repeated until therecord gap is filled.

FIG. 4 is a flow chart of a method of personal physiological sensorhistory backfill in accordance with the invention. The method 400 for alocal base device operable to wirelessly communicate with aphysiological sensor connected to a patient includes obtainingphysiological readings for the patient 402 at a predetermined interval;storing the physiological readings at the physiological sensor 404 assensor physiological readings; storing the physiological readings at thelocal base device 406 as historic physiological readings; obtaining acurrent physiological reading for the patient 408; transmitting thecurrent physiological reading to the local base device 410 in a currentreading message; detecting a record gap in the historic physiologicalreadings 412 between the current physiological reading and the historicphysiological readings; and filling the record gap in the historicphysiological readings with sensor physiological readings 414 from thephysiological sensor when the current reading message does not includethe sensor physiological readings to fill the record gap.

Once the record gap has been filled, the historic physiological readingscan be presented in a number of ways on the local base device, such asin a graph of physiological readings over several selectable periods oftime, e.g., 3, 6, 12, 24 hours, including color coding of data that hasbeen received in real time or has been backfilled; an icon depictingwhether the expected sensor information has been received; sensor alertsbased on high and/or low limits requested by the user; historic displayof readings by day or selected days; summaries of sensor statistics overa selected time period; and the like. The reconstructed historicphysiological readings provide the user and health care provider with anaccurate record of the user's physiological data.

The method 400 can be carried out on a variable data usage personalmedical system as described for FIGS. 1 & 2. Referring to FIG. 4, in oneembodiment, the local base device and physiological sensor in the method400 are an insulin pump and a glucose sensor, respectively. In oneembodiment, the local base device includes a local base device clock andthe physiological sensor includes a physiological sensor clock, and themethod 400 further includes synchronizing the local base device clockand the physiological sensor clock before the transmitting the currentphysiological reading to the local base device 410 in a current readingmessage.

Obtaining physiological readings for the patient 402 at a predeterminedinterval can include obtaining physiological readings from anyphysiological sensor connected to the patient and sensing aphysiological parameter. Exemplary physiological sensors include glucosesensors, heart-rate sensors, ECG sensors, pulse oximeters, bloodpressure sensors, respiration rate sensors, skin temperature sensors,electroencephalography (EEG) sensors, activity level sensors, vital signsensors, and the like. Those skilled in the art will appreciate that thephysiological sensor can be any sensor desired for a particularapplication. The predetermined interval can be selected as desired for aparticular application. In one embodiment, the predetermined intervalcan be five minutes.

Storing the physiological readings at the physiological sensor 404 assensor physiological readings can include storing the physiologicalreadings in flash memory included in the physiological sensor. In oneembodiment, the flash memory can store ten hours of physiologicalreadings.

Storing the physiological readings at the local base device 406 ashistoric physiological readings can include storing the physiologicalreadings in flash memory included in the local base device. In oneembodiment, the flash memory can store thirty days of physiologicalreadings. Exemplary local base devices include insulin pumps, cellpumps, local monitors, fitness monitors, smart phones, portable/wearablecomputing devices, watches, tablets, computers, and the like.

Obtaining a current physiological reading for the patient 408 caninclude obtaining the current physiological reading regardless ofwhether the physiological sensor is able to communicate wirelessly withthe local base device. In one embodiment, storing the physiologicalreadings at the local base device 406 may not have been possible beforeobtaining the current physiological reading because the wireless linkbetween the physiological sensor and the local base device was notavailable.

Transmitting the current physiological reading to the local base device410 in a current reading message can include transmitting the currentphysiological reading to the local base device after an interruptedwireless link between the physiological sensor and the local base devicehas been restored.

Detecting a record gap in the historic physiological readings 412between the current physiological reading and the historic physiologicalreadings can include determining at the local base device whether thereis a time gap between the current measurement time at which the currentphysiological reading was taken at the physiological sensor and the laststored glucose reading time for the most recent historic physiologicalreading. The time gap can occur from an interruption in the wirelesslink between the physiological sensor and the local base device, duringwhich time the local base devices are unable to receive physiologicalreadings for storage.

Filling the record gap in the historic physiological readings withsensor physiological readings 414 from the physiological sensor occurswhen the current reading message does not include the sensorphysiological readings to fill the record gap. In one embodiment, thecurrent reading message can include information in addition to thecurrent physiological reading. In one example, the current readingmessage can include the current physiological reading, the currentmeasurement time, and a predetermined packet number of physiologicalreadings immediately before the current physiological reading. When thecurrent reading message includes enough sensor physiological readings tofill the record gap, there is no need to obtain additional sensorphysiological readings, since the current reading message alreadyincludes enough information to complete the historic record. Forexample, when the record gap is missing six historic physiologicalreadings and the current reading message includes eight physiologicalreadings immediately before the current physiological reading, the sixphysiological readings in the current reading message immediately beforethe current physiological reading can be used to fill the record gap.

When the current reading message does not include the sensorphysiological readings to fill the record gap, additional sensorphysiological readings can be obtained from the physiological sensor tofill the record gap. For example, when the record gap is missing atwelve historic physiological readings and the current reading messageincludes eight physiological readings immediately before the currentphysiological reading, the first eight physiological readings in thecurrent reading message can be used to fill part of the record gap, buta record gap of four historic physiological readings remains. The fourhistoric physiological readings can be obtained from the physiologicalsensor to fill the remainder of the record gap. In one embodiment,filling the record gap in the historic physiological readings withsensor physiological readings 414 can further include repeatedlytransferring a predetermined packet number of sensor physiologicalreadings from the physiological sensor to the local base device toprovide the sensor physiological readings required to fill the recordgap.

Filling the record gap in the historic physiological readings withsensor physiological readings 414 can also account for additional eventsthat occurred during the time gap. Exemplary events include the patientmaking a time change at the local base device, the patient manuallyturning off/on the sensor, changing of the day through the passage oftime, and the like.

In one embodiment, filling the record gap in the historic physiologicalreadings with sensor physiological readings 414 further includesdetecting a Time Change marker that occurred during the record gap, theTime Change marker being stored at the local base device; and adjustinga user clock associated with the historic physiological readings in therecord gap on and after a time of the Time Change marker by a timechange value associated with the Time Change marker. The local basedevice can keep a user clock that is the local time at the patient'slocation as entered by the patient. The Time Change marker stored in thelocal base device indicates that the patient has changed the time. Forexample, when the patient travels from the western time zone to thecentral time zone in the United States, the patient can adjust the userclock by two hours to account for the time difference: a Time Changemarker is stored in the local base device with the associated time theuser clock adjustment is made, along with an associated time changevalue. When the Time Change marker appears during the record gap, thetime for the sensor physiological readings used to fill the record gapon or after the time the user clock adjustment was made can be adjustedby the time change value.

In one embodiment, filling the record gap in the historic physiologicalreadings with sensor physiological readings 414 further includesdetecting a Sensor Off marker that occurred during the record gap, theSensor Off marker being stored at the local base device; and assigning aSensor Off value to the historic physiological readings in the recordgap on and after a time of the Sensor Off marker. The patient can turnthe sensor off whenever they like, so that no data is recorded. Anyreadings received by the local base device from the physiological sensorwhen the patient has turned the sensor off are discarded and notprocessed. The Sensor Off marker stored in the local base deviceindicates that the patient has turned off the sensor. For example, whenthe patient has a meeting and does not want to be interrupted by thelocal base device, or the patient is in an area such as an airplanewhere no radio frequency transmission is permitted, the patient can turnoff the sensor. When the Sensor Off marker appears during the recordgap, the Sensor Off value can be used to fill the record gap on or afterthe time the sensor was turned off, so that no numerical value appearsfor those historic physiological readings. In one embodiment, a separateSensor Off value is assigned to and stored for each of the historicphysiological readings in the record gap in separate memory locations onand after a time of the Sensor Off marker. In another embodiment, asingle Sensor Off value is assigned to and stored across all thehistoric physiological readings in the record gap in one memory locationon and after a time of the Sensor Off marker, reducing the amount ofstorage required.

The method 400 can continue when the patient turns on the sensor. In oneembodiment, filling the record gap in the historic physiologicalreadings with sensor physiological readings 414 further includesdetecting a Sensor On marker that occurred during the record gap, theSensor On marker being stored at the local base device; and filling therecord gap in the historic physiological readings in the record gapafter a time of the Sensor On marker with sensor physiological readingsfrom the physiological sensor. When the Sensor On marker appears duringthe record gap, a special gap record is saved indicating no sensorreadings were written since the timestamp of the previously savedreading until the timestamp for the gap record; subsequent sensorphysiological readings from the physiological sensor can be used to fillthe record gap on or after the time the sensor was turned on.

In one embodiment, filling the record gap in the historic physiologicalreadings with sensor physiological readings 414 further includesaccounting for End of Day markers, which allows accurate retrieval andgraphing of the records for a particular date. In one embodiment, thefilling 414 further includes detecting an End of Day marker thatoccurred during the record gap, the End of Day marker being stored atthe local base device; and associating the End of Day marker with thehistoric physiological readings in the record gap at a time of the Endof Day marker. Thus, the End of Day markers are integrated into thebackfilled historic physiological readings ordered on the basis of theirtime of occurrence.

Start of Day (SOD) and End of Day (EOD) markers are saved in the sensorhistory area as they occur on the local base device, and define the dayboundaries used to retrieve and display or graph sensor physiologicalreadings requested by the user for a specific date. When sensorphysiological readings arrive at their expected periodic interval andare saved in the sensor history area of the local base device, i.e.,during normal operation, the SOD and EOD markers are also saved in thesensor history area of the local base device at the time they occur todefine the day boundaries used for daily history retrieval of the sensorphysiological readings. When the sensor physiological readings have notarrived as expected and are late when an EOD event occurs, e.g., whencommunication has been lost between the local base device and thephysiological sensor, an EOD marker is not saved in sensor history ofthe local base device, but is stored elsewhere in the local base devicefor later EOD marker processing when the stored EOD marker can bewritten in an integrated manner with the backfilled sensor physiologicalreadings. This allows the daily history retrieval of sensorphysiological information to accurately be presented to the user whenrequested.

The method 400 can also account for situations in which the number ofmissing historic physiological readings in the record gap is greaterthan the number of sensor physiological readings available in thephysiological sensor. In one embodiment, filling the record gap in thehistoric physiological readings with sensor physiological readings 414further includes assigning a Gap Fill value to the historicphysiological readings in the record gap before a fillable start timedefined as time of the current physiological reading less a maximumphysiological sensor storage time. For example, when the record gap is12 hours and the maximum physiological sensor storage time is 10 hoursof physiological readings, the Gap Fill value can be used to fill therecord gap from the beginning of the record gap until the fillable starttime two hours later, so that it is apparent that no numerical valuesare available for those historic physiological readings.

The method 400 can also account for errors which occur during sensorhistory backfill. When the pump history data is corrupted, as indicatedby cyclic redundancy check (CRC) error when reading the pump historydata from the storage medium, the insulin pump aborts the sensor historybackfill. When a block of the pump history data is not a completelywritten (unclosed) because of an unexpected reset, the insulin pumpaborts the sensor history backfill. When a block of the pump historydata is unexpectedly empty, the insulin pump aborts the sensor historybackfill. When a block signature (CRC and datalength) are both zeroindicating a bad CRC on the original write with no data loss, the blockwith the bad block signature is ignored and the sensor history backfillcontinues with reading the next block. When the pump history data iscorrupted, as indicated by cyclic redundancy check (CRC) error whenreading the pump history data delivered to the processing unit, theinsulin pump aborts the sensor history backfill. When the insulin pumpaborts the sensor history backfill, the pump history data in the storagemedium can be returned to a condition to preserve the integrity ofsubsequent data searching and retrieval. In one embodiment, the insulinpump can save critical data required for sensor history backfill tononvolatile memory, so that the data history backfill can continue fromthe point of interruption when the insulin pump resets during sensorhistory backfill.

The method 400 can be applied as discussed below when the local basedevice is an insulin pump and the physiological sensor is a glucosesensor connected to the patient, the insulin pump being operable towirelessly communicate with the glucose sensor.

Obtaining physiological readings for the patient 402 at a predeterminedinterval can include obtaining glucose readings for the patient at apredetermined interval, each of the glucose readings being associatedwith a glucose reading time.

Storing the physiological readings at the physiological sensor 404 assensor physiological readings can include storing a predeterminedstorage number of the glucose readings at the glucose sensor with theassociated glucose reading time, the predetermined storage number beinggreater than or equal to one and greater than a predetermined packetnumber.

Obtaining a current physiological reading for the patient 408 caninclude measuring a current glucose reading for the patient at a currentmeasurement time.

Transmitting the current physiological reading to the local base device410 in a current reading message can include transmitting from theglucose sensor to the insulin pump a current message including thecurrent glucose reading, the current measurement time, and thepredetermined packet number of the glucose readings immediately beforethe current glucose reading, the predetermined packet number beinggreater than or equal to zero.

Detecting a record gap in the historic physiological readings 412between the current physiological reading and the historic physiologicalreadings can include retrieving a last stored glucose reading time fromthe insulin pump memory; and calculating a time gap between the currentmeasurement time and the last stored glucose reading time.

Filling the record gap in the historic physiological readings withsensor physiological readings 414 from the physiological sensor when thecurrent reading message does not include the sensor physiologicalreadings to fill the record gap can include setting a backfill starttime equal to the last stored glucose reading time when the time gap isgreater than a packet duration defined as the predetermined intervalmultiplied by the predetermined packet number; requesting the glucosesensor to transmit to the insulin pump the predetermined packet numberof the glucose readings immediately after the backfill start time;storing the predetermined packet number of the glucose readingsimmediately after the backfill start time in the insulin pump; addingthe packet duration to the backfill start time; and repeating therequesting, the storing, and the adding when a backfill end time definedas the backfill start time less the packet duration is less than thecurrent measurement time.

It is important to note that FIGS. 1-4 illustrate specific applicationsand embodiments of the invention, and are not intended to limit thescope of the present disclosure or claims to that which is presentedtherein. Upon reading the specification and reviewing the drawingshereof, it will become immediately obvious to those skilled in the artthat myriad other embodiments of the invention are possible, and thatsuch embodiments are contemplated and fall within the scope of thepresently claimed invention.

While the embodiments of the invention disclosed herein are presentlyconsidered to be preferred, various changes and modifications can bemade without departing from the spirit and scope of the invention. Thescope of the invention is indicated in the appended claims, and allchanges that come within the meaning and range of equivalents areintended to be embraced therein.

The invention claimed is:
 1. A method of sensor history backfill for alocal base device operable to wirelessly communicate with aphysiological sensor connected to a patient, the method comprising:obtaining physiological readings for the patient at a predeterminedinterval; storing the physiological readings at the physiological sensoras sensor physiological readings; transmitting the physiologicalreadings from the physiological sensor to the local base device; storingthe physiological readings at the local base device as historicphysiological readings; obtaining a current physiological reading forthe patient; transmitting the current physiological reading from thephysiological sensor to the local base device in a current readingmessage; detecting at the local base device a record gap in the historicphysiological readings between the current physiological reading and thehistoric physiological readings; identifying missing physiologicalreadings in the record gap; transmitting a request for the missingphysiological readings from the local base device to the physiologicalsensor when the current reading message does not include the sensorphysiological readings to fill the record gap; selecting sensorphysiological readings for the missing physiological readings;transmitting the selected sensor physiological readings from thephysiological sensor to the local base device; and filling the recordgap in the historic physiological readings with the selected sensorphysiological readings from the physiological sensor.
 2. The method ofclaim 1 wherein the local base device is an insulin pump and thephysiological sensor is a glucose sensor.
 3. The method of claim 1wherein the local base device includes a local base device clock and thephysiological sensor includes a physiological sensor clock, the methodfurther comprising synchronizing the local base device clock and thephysiological sensor clock before transmitting the current physiologicalreading from the physiological sensor to the local base device in thecurrent reading message.
 4. The method of claim 1 wherein the fillingfurther comprises repeatedly transferring a predetermined packet numberof sensor physiological readings from the physiological sensor to thelocal base device to provide the sensor physiological readings requiredto filling the record gap.
 5. The method of claim 1 wherein the fillingfurther comprises: detecting a Time Change marker that occurred duringthe record gap, the Time Change marker being stored at the local basedevice; and adjusting a user clock associated with the historicphysiological readings in the record gap on and after a time of the TimeChange marker by a time change value associated with the Time Changemarker.
 6. The method of claim 1 wherein the filling further comprises:detecting a Sensor Off marker that occurred during the record gap, theSensor Off marker being stored at the local base device; and assigning aSensor Off value to the historic physiological readings in the recordgap on and after a time of the Sensor Off marker.
 7. The method of claim1 wherein the filling further comprises: detecting a Sensor On markerthat occurred during the record gap, the Sensor On marker being storedat the local base device; and filling the record gap in the historicphysiological readings in the record gap after a time of the Sensor Onmarker with sensor physiological readings from the physiological sensor.8. The method of claim 1 wherein the filling further comprises:detecting an End of Day marker that occurred during the record gap, theEnd of Day marker being stored at the local base device; and associatingthe End of Day marker with the historic physiological readings in therecord gap at a time of the End of Day marker.
 9. The method of claim 1wherein the filling further comprises: assigning a Gap Fill value to thehistoric physiological readings in the record gap before a fillablestart time defined as time of the current physiological reading less amaximum physiological sensor storage time.
 10. The method of claim 1,further comprising: detecting an error during sensor history backfill;and aborting the filling in response to detecting the error.
 11. Amethod of sensor history backfill for a local base device operable towirelessly communicate with a physiological sensor connected to apatient, the method comprising: obtaining physiological readings for thepatient at a predetermined interval, each of the physiological readingsbeing associated with a physiological reading time; storing apredetermined storage number of the physiological readings at thephysiological sensor with the associated physiological reading time, thepredetermined storage number being greater than or equal to one andgreater than a predetermined packet number; measuring a currentphysiological reading for the patient at a current measurement time;transmitting from the physiological sensor to the local base device acurrent message including the current physiological reading, the currentmeasurement time, and the predetermined packet number of thephysiological readings immediately before the current physiologicalreading, the predetermined packet number being greater than or equal tozero; retrieving a last stored physiological reading time from the localbase device memory; calculating a time gap between the currentmeasurement time and the last stored physiological reading time; settinga backfill start time equal to the last stored physiological readingtime when the time gap is greater than a packet duration defined as thepredetermined interval multiplied by the predetermined packet number;requesting the physiological sensor to transmit to the local base devicethe predetermined packet number of the physiological readingsimmediately after the backfill start time; storing the predeterminedpacket number of the physiological readings immediately after thebackfill start time in the local base device; adding the packet durationto the backfill start time; and repeating the requesting, the storing,and the adding when a backfill end time defined as the backfill starttime less the packet duration is less than the current measurement time.12. The method of claim 11 wherein the local base device is an insulinpump and the physiological sensor is a glucose sensor.
 13. The method ofclaim 11 wherein the local base device includes a local base deviceclock and the physiological sensor includes a physiological sensorclock, the method further comprising synchronizing the local base deviceclock and the physiological sensor clock before transmitting the currentphysiological reading from the physiological sensor to the local basedevice in the current reading message.
 14. The method of claim 11,further comprising: detecting a Time Change marker that occurred duringthe time gap, the Time Change marker being stored at the local basedevice; and adjusting a user clock associated with physiologicalreadings stored at the local base device on and after a time of the TimeChange marker by a time change value associated with the Time Changemarker.
 15. The method of claim 11, further comprising: detecting aSensor Off marker that occurred during the time gap, the Sensor Offmarker being stored at the local base device; and assigning a Sensor Offvalue to physiological readings stored at the local base device on andafter a time of the Sensor Off marker.
 16. The method of claim 11,further comprising: detecting a Sensor On marker that occurred duringthe time gap, the Sensor On marker being stored at the local basedevice; and filling the time gap after a time of the Sensor On markerwith sensor physiological readings from the physiological sensor. 17.The method of claim 11, further comprising: detecting an End of Daymarker that occurred during the time gap, the End of Day marker beingstored at the local base device; and associating the End of Day markerwith physiological readings stored at the local base device at a time ofthe End of Day marker.
 18. The method of claim 11, further comprising:assigning a Gap Fill value to physiological readings stored at the localbase device before a fillable start time defined as time of the currentphysiological reading less a maximum physiological sensor storage time.19. The method of claim 11, further comprising: detecting an errorduring sensor history backfill; and aborting the filling in response todetecting the error.